Force pulse shaping member for percussion tool

ABSTRACT

A member comprising the shank or an integral shank-drill rod for a percussion rock drill and having a force-deflection or stiffness characteristic similar to the effective stiffness of the earth formation to be penetrated. The member is adapted to be removably inserted into the rock drill in blow-receiving relationship with a reciprocating hammer element. The member is also operable to be a rotation transmitting means for rotating an extension drill string.

United States [151 3,6 3 l Cnyne et al. 1 Feb. S, 11972 [54] FORCE PULSESHAPING MEMBER FOR 3,368,634 2/1968 Lear ..l73/l05 PERCUSSION T L3,382,932 5/1968 Wise ..173/ 135 [72] Inventors: Merton W. Coyne,Arvada; Dieter it. a Emmner hmes A Le ink Palauro, Denver, both Of COlO.:3;, E Martin. pp [73] Assignee: Gardner-Denver Company, Quincy, Ill.

22 Filed: May 18, 1970 [571 ABSTRACT 211 Appl. No.: 38,422 l 7 W V V Amember comprising the shank or an integral shank-dull rod for apercussion rock drill and having a force-deflection or [52] US. Cl..l73/105, l73/ 133, 175/320 tiff h t i ti similar to the effectivestiffness of the [Si lint. Cl. ..B25d 9/00, EZlb 17/00 th f m ti n to bepenetrated, The member is adapted to [58] Field of Search... .l73/l33,134, 135,104,1 5; be removably inserted into the rock drill inblow-receiving 175/320 relationship with a reciprocating hammer element.The member is also operable to be a rotation transmitting means [56]References Cited for rotating an extension drill string.

UNlTED STATES PATENTS 7 Claims 4 Drawing Figures 3,044,448 7/1962 Curtiset al. ..l73/l05 i i X &

ii'l l'i 20 /0 M H /6- l8 34 56 36 i 2 I Z i 44 43 i 50 i 56 x 52 I IFORCE PULSE SHAPING ER FOR PERCUSSION TOOL BACKGROUND OF THE INVENTIONThe disclosure of US. Pat No. 3,382,932 to B. A. Wise teaches thatessentially all earth formations being penetrated by local crushing orchipping in the bore hole exhibit a forcedeflection characteristic orstiffness. The Wise patent also reaches that, by providing a so-calledspring member in a percussion rock drill, a force pulse may betransmitted to the earth formation which results in more desirableenergy transfer to the formation and, accordingly, greater penetrationrates. This spring member as disclosed in the Wise patent preferably hasa stiffness characteristic similar to that of the effective stiffness ofthe formation to be penetrated and develops a force pulse having ashape, when graphically plotted as a function of time, which alsoresults in lower stress levels imposed on the drill rod and couplingmembers.

Following the teaching of the above-mentioned patent the necessarydimensions of a force pulse shaping member for most percussion rockdrills, including the drill disclosed in the Wise patent, result in amember which is a substantially slender rod located in blow-receivingrelationship with the drill hammer element. However, the pulse shapingspring of Wise is positioned entirely within the drill housing andthereby substantially lengthens the drill structure proper. Thiselongation of the drill is undesirable in that it makes the drillconsiderably heavier and more bulky. Furthermore, for rock drills whichare movably mounted on elongated feed supports, lengthening of the drillitself requires a longer and heavier support. Conversely, if the drillsupport is not lengthened, the effective feed length of the support isreduced and shorter sections of extension drill rod are required to beused for deep hole drilling. Short drill rod sections require morefrequent operations for adding or subtracting drill rods to an extensiondrill string with the attendant increase in time required to completethe operation of drilling a hole.

Since the force pulse shaping member itself it highly stressed and islikely to incur a structural failure, it follows that, with the forcepulse shaping member housed entirely within the drill, a catastrophicfailure may easily cause damage to the drill itself and in any eventrequires considerable time to be replaced as the drill itself must besubstantially disassembled.

SUMMARY OF THE INVENTION The present invention provides for a forcepulse shaping member for a percussion tool such as a fluid operated rockdrill or the like wherein said member comprises a separate shank or anintegral section of a one piece drill rod. In accordance with thepresent invention a force pulse shaping member is provided which isremovably insertable into one end of a percussion rock drill inblow-receiving relationship with a reciprocating hammer element. Theforce pulse shaping shank member may be adapted at the opposite end toinclude means for releasably coupling said member to a forcetransmitting means comprising an extension drill string made up of aplurality of rods coupled end to end and including a formationpenetrating bit. Alternatively, the force pulse shaping member of thepresent invention may comprise an integral shanlulrill rod for use indrilling holes where extension members are not required.

Contrary to prior teaching in the art of force pulse shaping the presentinvention also provides a pulse shaping member which is operable to be atorque transmitting coupling for rotating a percussive drill string.

The principal object of the present invention is to provide a forcepulse shaping member as suggested by Wise which can be advantageouslyused with more conventional percussion rock drills without altering thedrill structure itself, but yet providing improved penetration rates andlonger life for drill string members. By incorporating a pulse shapingmember as a shank or an integral shank-drill rod the drill housing isnot required to be lengthened as with prior art, internally positioned,force pulse shaping members. Accordingly, the weight and structuralcomplexity of the drill are not increased, Furthermore, by providing thepulse shaping member whose length becomes part of the useful drill rodlength, deeper holes may be drilled in a single traversal of feedsupport mounted drills, and with lighter hand positioned tools such asfeed leg drills as well. An advantage of the present invention alsoresides in the fact that should a structural failure be encountered withthe force pulse shaping shank, said shank may be quickly replaced.Moreover, a catastrophic structural failure of such a shank member isnot likely to cause damage to the drill proper as a substantial portionof the highly stressed force pulse shaping section is not housed withinthe drill.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal view,partially sectioned, of a fluid operated percussion rock drill includingthe force pulse shaping member of the present invention.

FIG. 2 is a transverse section view taken along the line 2-2 of FIG. 1.

FIG. 3 is a side elevation of an exemplary mobile rock drill unitutilizing the present invention.

FIG. 4 is a view of an alternate embodiment of the present inventioncomprising an integral shank-drill rod member including a formationpenetrating bit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention aforce pulse shaping member or so-called spring comprises a separateshank portion for a fluid operated percussion rock drill. The essentialsubject matter for determining the stiffness characteristic and thedimen sional relationships for the force pulse shaping shank hereindisclosed may be found in the disclosure and teaching of US. Pat. No.3,382,932 to B. A. Wise. Although the embodiments of a shank disclosedherein are utilized in an otherwise substantially conventional fluidoperated rock drill, it is contemplated that the teaching of the presentinvention may be applied to the general type of percussion tooldisclosed in the Wise patent as well as other types of percussion toolswhich operate to deliver repeated impact blows to a force-transmittingmeans.

Referring to FIG. 1, a pressure fluid operated percussion rock drill isillustrated and generally designated by the numeral 10. The rock drill10 is of a type well known and includes a housing 12 having acylindrical bore 14 therein. A hammer element 16 disposed in the bore 14is operable in response to the alternate valving of pressure fluid, suchas compressed air, to chambers 18 and 20 formed in the bore 14, toreciprocate rapidly therein. A pressure fluid distributing valve 22forms one end of the bore 14 and is operable to receive pressure fluid,from a supply not shown, and alternately valve quantities of said fluidto the chambers I8 and 20 in a manner well known.

The drill 10 is also characterized by motor means 24 drivably connectedto a rotatable chuck member 26 by means of a drive shaft 28 and a pinion30, the latter drivably engaged with gear means 32 formed on the chuckmember 26 by means of a drive shaft The chuck member 26 is rotatablyhoused in the forward part 42 of the drill housing 12. The chuck member26 includes a tight fitting sleeve 34 which nonrotatably journals amember 36 by means of complementary splines 40 and flutes 38 located onthe segment 39 of the member 36 (see FIG. 2). The member 36 is removablyinsertable through the opening 43 into the chuck member 26 and isretained in the chuck member by means of a retainer 44.

The member 36 is commonly known in the art of percussion rock drills asa shank. The shank 36 is primarily an end portion of aforce-transmitting means which usually includes one or more elongatedrodlike members threadedly coupled in endto-end relationship to form anextension drill string. Additionally, the shank 36 includes a surface 46operable to receive percussion blows from the hammer element 16.Furthermore, the shank 36 is operable to be a torque transmitting memberfor transmitting rotational motion to the coupled rod sections forrotating a rock penetrating bit member attached to the opposite end ofthe aforementioned extension drill string.

For convenience in handling the drill l and to make practical theadditional of drill rods to lengthen the extension drill string theshank 36 is designed to extend beyond the forward housing part 42 of thedrill no more than is necessary to provide for the coupling threads 48.The shank 36 has a somewhat elongated section 50 which is desirablyinterposed between the shoulder 52 adjacent the threads 48 and aretaining collar 54, the latter comprising means operable to engage theretainer 44 to prevent unwanted displacement of the shank from the chuckmember 26. The dimensions of the elongated section 50 may be determinedfrom the procedure disclosed in US. Pat. 3,382,932 regarding springstiffness and cross-sectional area of a force pulse shaping member. Theshank 36 also includes a cleansing fluid passage 56 including a portion58 for telescopically receiving a cleansing fluid tube 60. Due to thefact that the shank 36 must, in effect, act as a compression spring, itis desirably made of a high strength elastic material such as an alloysteel or titanium alloy.

Referring to FIG. 3 a typical mobile rock drill unit is shown generallydesignated by the numeral 62. The unit 62 includes a crawler-typeundercarriage 64 and a movable positioning member 66 to which isattached an elongated drill support 68. The drill is slidably mounted onthe support 68 and is operable to be fed reversibly therealong bysuitable means, not shown.

In FIG. 3 the drill 10 is engaged with an extension drill string 70comprising elongated drill rods 72 releasably coupled together and tothe shank 36 by a cooperating internal and external threaded portionssuch as shown in FIG. 1 wherein the external threads 48 are engaged withan internal threaded portion 74 on the rod 72. The distal end of thedrill string 70 has coupled thereto a bit 76 operable to penetrate anearth formation 78 to form a hole 80 in response to the transmission offorce pulses form the drill through the drill string 70. As shown inFIG. 3, the lower end of the drill support 68 includes a drill rod guide82 commonly known as a centralizer. The centralizer 82 rotatablyjournals the rod 72 and may be one of several well-known types.

Referring to FIG. 4 an integral shank-drill rod member is illustratedand generally designated by the numeral 86. The shank-drill rod member86 is commonly known as a single pass rod and is used in applicationswherein sufficient hole depth is obtained with one traversal of thedrill 10 along the support 68. Such integrally formed shank-drill rodsare also widely used in lightweight portable rock drills used inundcrground mining and the like. The shank-drill rod member 86 comprisesa force pulse shaping and transmitting means having a section 88 formedin accordance with the teaching of the aforementioned U.S. Pat. No.3,382,932 to provide a force-deflection characteristic similar to thatof the formation to be penetrated. The member 86 also includes a segment90 including flutes 92 and a retaining collar 94 whereby the member 86may be inserted in the chuck member 26 of the drill 10 in the samemanner as the shank 36. The shank-drill rod member 86 also includes asurface 96 operable to be in blow-receiving relationship with the hammerelement 16, and a cleansing fluid passage 98 leading to openings 100(one shown) adjacent a formation penetrating bit end 102. As shown inFIG. 4 the bit 102 is integrally formed as part of the shank-drill rodmember 86 with the exception of the replaceable insert 104. However, theend opposite the blow-receiving end of the member 86 could also beprovided with a tapered or threaded portion for removably coupling adetachable bit thereto in a manner well known.

It is contemplated that the shank-drill rod member 86 could be desirablyformed of an elastic material such as alloy steel initially made up ofseparate segments and 106, the latter comprising drill rod and the forcepulse shaping section 88. The segments 90 and 106 could be separatelyformed and joined by so-called friction welding at the transverseinterface 108 to thereby enjoy the benefits of the teaching of US. Pat.No. 3,295,613 to F. R. Anderson.

A particularly advantageous aspect of incorporating the force pulseshaping member into the shank 36 or the integral shank-drill rod 86 maybe noted from the drawing in that additional effective drill stringlength is obtained by providing for the force pulse shaping section tobe positioned substantially exterior of the drill 10. That is, eachtraversal of the drill 10 down the support 68 is limited only by theengagement of the forward part of the drill casing 42 with thecentralizer 82. Accordingly, if the force pulse shaping memberwas'housed entirely within the drill casing the effective length of eachtraversal along the support would be less than is obtained with thepresent invention due to the fact that the length of the drill itselfwould have to be increased.

A further advantage of the present invention resides in the fact thatalthough the provision of a force pulse shaping member in a percussiondrill string results in more efficient energy transfer to the rockformation and lower stresses in the extension drill rods and couplings,the pulse shaping member itself becomes highly stressed. Therefore,should the force pulse shaping shank 36 or the integral shank-drill rod86 incur a structural failure, it may be quickly replace withoutdisassembly of the drill l0 and furthermore it is unlikely that anydamage to the drill would result from such a failure as the highlystressed force pulse shaping section is located substantially outside ofthe drill structure.

What is claimed is:

1. In a percussion tool for delivering impact blows to a load such as anearth formation or the like:

a housing including a chuck member rotatably mounted in said housing;

a reciprocable hammer element;

force transmitting means including a formation penetrating bit portionoperable to transmit percussive blows from said hammer element to saidload; and,

an elastic member comprising a shank portion of said force transmittingmeans located between said hammer element and said load for deliveringforce pulses from said hammer element to said force transmitting meansand having a stiffness similar to the effective stifi'ness of said load,said shank portion having one end connected to said force transmittingmeans, and the opposite end of said shank portion is removablyinsertable in said chuck member whereby said shank portion is joumaledby said chuck member nonrotatably with respect to said chuck member.

2. The invention set forth in claim 1 wherein:

said shank portion includes a surface on said opposite end operable tobe in blow-receiving contact with said hammer element.

3. The invention set forth in claim 1 wherein:

said shank portion comprises a torque-transmitting coupling between saidpercussion tool and said force-transmitting means.

4. In a percussion tool for delivering impact blows to a load such as anearth formation or the like;

a reciprocable hammer element;

force transmitting means including a formation penetrating bit portionoperable to transmit percussive blows from said hammer element to saidload;

an elastic member comprising a shank portion of said force transmittingmeans located between said hammer element and said load for deliveringforce pulses from said hammer element to said force transmitting meansand having a stiffness similar to the effective stiffness of said load,said shank portion including means at one end for releasably connectingsaid shank portion to said force transmitting means;

said tool including receiving means for receiving the opposite end ofsaid shank portion, said shank portion being removably insertable insaid receiving means;

said tool including retaining means for removably retaining said shankportion in said receiving means; and,

means on said shank portion engageable with said retaining means.

5. The invention set forth in claim 1 wherein:

said shank portion includes a section interposed between said meansengageable with said retaining means and said one end having a stiffnesssimilar to the effective stiffness of said load.

6. The invention set forth in claim 5 wherein:

said section of said shank is substantially exterior of said tool whensaid shank is retained in said tool.

7. In a percussion tool for delivering impact blows to a load such as anearth formation or the like;

a reciprocable hammer element; force transmitting means including aformation penetrating bit portion operable to transmit percussive blowsfrom said hammer element to said load;

an elastic member comprising a shank portion of said force transmittingmeans located between said hammer element and said load for deliveringforce pulses from said hammer element to said force transmitting meansand having a stiffness similar to the effective stiffness of said load;

said tool including receiving means for receiving one end of said shankportion, said shank portion being removably insertable in said receivingmeans;

said shank portion including an elongated integral segment of said forcetransmitting means comprising a percussion drill rod; and

said shank portion including a section interposed between said drill rodsegment and said one end having a stiffness similar to the effectivestiffness of said load.

Patent No; Dated e ry 8, 1972 Inventor( Merton coyne and Dleter K.Palauro It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 10, change "reaches" to teaches Column 2, line 62, placea period after "26" and delete "by means".

Column 2, line 63 delete "of a drive shaft".

Column 3, line 9, change "additional" to addition Column 5, line 8,change "1" to 4 Signed and sealed this 28th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesti'ng Officer Commissionerof Patents FORM PC4950 (10-69) USCOMM-DC 6O37B-P69 11.5, GOVEHNMENTFRNTING OFFICE: I969 O '35G-331|

1. In a percussion tool for delivering impact blows to a load such as anearth formation or the like: a housing including a chuck memberrotatably mounted in said housing; a reciprocable hammer element; forcetransmitting means including a formation penetrating bit portionoperable to transmit percussive blows from said hammer element to saidload; and, an elastic member comprising a shank portion of said forcetransmitting means located between said hammer element and said load fordelivering force pulses from said hammer element to said forcetransmitting means and having a stiffness similar to the effectivestiffness of said load, said shank portion having one end connected tosaid force transmitting means, and the opposite end of said shankportion is removably insertable in said chuck member whereby said shankportion is journaled by said chuck member nonrotatably with respect tosaid chuck member.
 2. The invention set forth in claim 1 wherein: saidshank portion includes a surface on said opposite end operable to be inblow-receiving contact with said hammer element.
 3. The invention setforth in claim 1 wherein: said shank portion comprises atorque-transmitting coupling between said percussion tool and saidforce-transmitting means.
 4. In a percussion tool for delivering impactblows to a load such as an earth formation or the like; a reciprocablehammer element; force transmitting means including a formationpenetrating bit portion operable to transmit percussive blows from saidhammer element to said load; an elastic member comprising a shankportion of said force transmitting means located between said hammerelement and said load for delivering force pulses from said hammerelement to said force transmitting means and having a stiffness similarto the effective stiffness of said load, said shank portion includingmeans at one end for releasably connecting said shank portion to saidforce transmitting means; said tool including receiving means forreceiving the opposite end of said shank portion, said shank portionbeing removably insertable in said receiving means; said tool includingretaining means for removably retaining said shank portion in saidreceiving means; and, means on said shank portion engageable with saidretaining means.
 5. The invention set forth in claim 1 wherein: saidshank portion includes a section interposed between said meansengageable with said retaining means and said one end having a stiffnesssimilar to the effective stiffness of said load.
 6. The invention setforth in claim 5 wherein: said section of said shank is substantiallyexterior of said tool when said shank is retained in said tool.
 7. In apercussion tool for delivering impact blows to a load such as an earthformation or the like; a reciprocable hammer element; force transmittingmeans including a formation penetrating bit portion operable to transmitpercussive blows from said hammer element to said load; an elasticmember comprising a shank portion of said force transmitting meanslocated between said hammer element and said load for delivering forcepulses from said hammer element to said force transmitting means andhaving a stiffness similar to the effective stiffness of said load; saidtool including receiving means for receiving one end of said shankportion, said shank portion being removably insertable in said receivingmeans; said shank portion including an elongated integral segment ofsaid force transmitting means comprising a percussion drill rod; andsaid shank portion including a section interposed between said drill rodsegment and said one end having a stiffness similar to the effectivestiffness of said load.